I can verify what iloman wrote. Disabling that service has stopped the flickering.
For people who cannot find this option:
1. go to System settings in the menu
2. Press the Advanced tab
3. Select the Service Manager
4. Stop the Detecting RANDR(monitor) changes
5. Also tick the checkbox use, so it won't startup again
6. Press apply and close the window
I can verify what iloman wrote. Disabling that service has stopped the flickering.
For people who cannot find this option:
1. go to System settings in the menu
2. Press the Advanced tab
3. Select the Service Manager
4. Stop the Detecting RANDR(monitor) changes
5. Also tick the checkbox use, so it won't startup again
6. Press apply and close the window
I hope you're flickering is gone now!